1. Field of the Invention
The present invention relates to 8-Azaprostaglandin carbonate and thiocarbonate analogues as therapeutic agents, e.g. for the management of glaucoma.
2. Description of Related Art
Ocular hypotensive agents are useful in the treatment of a number of various ocular hypertensive conditions, such as post-surgical and post-laser trabeculectomy ocular hypertensive episodes, glaucoma, and as presurgical adjuncts.
Glaucoma is a disease of the eye characterized by increased intraocular pressure. On the basis of its etiology, glaucoma has been classified as primary or secondary. For example, primary glaucoma in adults (congenital glaucoma) may be either open-angle or acute or chronic angle-closure. Secondary glaucoma results from pre-existing ocular diseases such as uveitis, intraocular tumor or an enlarged cataract.
The underlying causes of primary glaucoma are not yet known. The increased intraocular tension is due to the obstruction of aqueous humor outflow. In chronic open-angle glaucoma, the anterior chamber and its anatomic structures appear normal, but drainage of the aqueous humor is impeded. In acute or chronic angle-closure glaucoma, the anterior chamber is shallow, the filtration angle is narrowed, and the iris may obstruct the trabecular meshwork at the entrance of the canal of Schlemm. Dilation of the pupil may push the root of the iris forward against the angle, and may produce pupilary block and thus precipitate an acute attack. Eyes with narrow anterior chamber angles are predisposed to acute angle-closure glaucoma attacks of various degrees of severity.
Secondary glaucoma is caused by any interference with the flow of aqueous humor from the posterior chamber into the anterior chamber and subsequently, into the canal of Schlemm. Inflammatory disease of the anterior segment may prevent aqueous escape by causing complete posterior synechia in iris bombe, and may plug the drainage channel with exudates. Other common causes are intraocular tumors, enlarged cataracts, central retinal vein occlusion, trauma to the eye, operative procedures and intraocular hemorrhage.
Considering all types together, glaucoma occurs in about 2% of all persons over the age of 40 and may be asymptotic for years before progressing to rapid loss of vision. In cases where surgery is not indicated, topical b-adrenoreceptor antagonists have traditionally been the drugs of choice for treating glaucoma.
Certain eicosanoids and their derivatives have been reported to possess ocular hypotensive activity, and have been recommended for use in glaucoma management. Eicosanoids and derivatives include numerous biologically important compounds such as prostaglandins and their derivatives. Prostaglandins can be described as derivatives of prostanoic acid which have the following structural formula: 
Various types of prostaglandins are known, depending on the structure and substituents carried on the alicyclic ring of the prostanoic acid skeleton. Further classification is based on the number of unsaturated bonds in the side chain indicated by numerical subscripts after the generic type of prostaglandin [e.g. prostaglandin E1 (PGE1), prostaglandin E2 (PGE2)], and on the configuration of the substituents on the alicyclic ring indicated by xcex1 or xcex2 [e.g. prostaglandin F2xcex1 (PGF2xcex2)].
Prostaglandins were earlier regarded as potent ocular hypertensives, however, evidence accumulated in the last decade shows that some prostaglandins are highly effective ocular hypotensive agents, and are ideally suited for the long-term medical management of glaucoma (see, for example, Bito, L. Z. Biological Protection with Prostaglandins, Cohen, M. M., ed., Boca Raton, Fla., CRC Press Inc., 1985, pp. 231-252; and Bito, L. Z., Applied Pharmacology in the Medical Treatment of Glaucomas Drance, S. M. and Neufeld, A. H. eds., New York, Grune and Stratton, 1984, pp. 477-505. Such prostaglandins include PGF2xcex1, PGF1xcex1, PGE2, and certain lipid-soluble esters, such as C1 to C2 alkyl esters, e.g. 1-isopropyl ester, of such compounds.
Although the precise mechanism is not yet known experimental results indicate that the prostaglandin-induced reduction in intraocular pressure results from increased uveoscleral outflow [Nilsson et.al., Invest. Ophthalmol. Vis. Sci. (suppl), 284 (1987)].
The isopropyl ester of PGF2xcex1 has been shown to have significantly greater hypotensive potency than the parent compound, presumably as a result of its more effective penetration through the cornea. In 1987, this compound was described as xe2x80x9cthe most potent ocular hypotensive agent ever reportedxe2x80x9d [see, for example, Bito, L. Z., Arch. Ophthalinol. 105. 1036 (1987), and Siebold et.al., Prodrug 5 3 (1989)].
Whereas prostaglandins appear to be devoid of significant intraocular side effects, ocular surface (conjunctival) hyperemia and foreign-body sensation have been consistently associated with the topical ocular use of such compounds, in particular PGF2xcex1 and its prodrugs, e.g., its 1-isopropyl ester, in humans. The clinical potentials of prostaglandins in the management of conditions associated with increased ocular pressure, e.g. glaucoma are greatly limited by these side effects.
In a series of co-pending United States patent applications assigned to Allergan, Inc. prostaglandin esters with increased ocular hypotensive activity accompanied with no or substantially reduced side-effects are disclosed. The co-pending U.S. Ser. No. 596,430 (filed 10 Oct. 1990, now U.S. Pat. No. 5,446,041), relates to certain 11-acyl-prostaglandins, such as 11-pivaloyl, 11-acetyl, 11-isobutyryl, 11-valeryl, and 11-isovaleryl PGF2xcex1. Intraocular pressure reducing 15-acyl prostaglandins are disclosed in the co-pending application U.S. Ser. No. 175,476 (filed 29 Dec. 1993). Similarly, 11,15- 9,15 and 9,11-diesters of prostaglandins, for example 11,15-pivaloyl PGF2xcex1 are known to have ocular hypotensive activity. See the co-pending patent applications U.S. Ser. No. 385,645 (filed 7 Jul. 1989, now U.S. Pat. No. 4,994,274), Ser. No. 584,370 (filed 18 Sep. 1990, now U.S. Pat. No. 5,028,624) and Ser. No. 585,284 (filed 18 Sep. 1990, now U.S. Pat. No. 5,034,413). The disclosures of all of these patent applications are hereby expressly incorporated by reference.
8-Azaprostaglandin analogs are disclosed in PCT Patent Applications WO 01/46140 A1, WO 02/042268 A2, WO 02/24647 A1, WO 03/007941 A1, EP 1 121 939 A2 and Japanese Patent 2001-233792.
The present invention provides therapeutic agents comprising a compound of formula I 
wherein a wavy line represents either the xcex1 configuration or the xcex2 configuration and a dotted line represents the presence or absence of a double bond;
A represents a single bond or a cis double (alkene) bond or a triple (alkyne) bond;
X is CO2R, CONR2, CH2OR, P(O)(OR)2, CONRSO2R, SONR2 or 
n is 0 or an integer of from 1 to 4;
x and y are 0 or 1, provided however when x is 1, y is 0 and when x is 0,
y is 1;
Z is S or O;
R is H or R1;
R1 is C1-C5 lower alkyl or alkenyl;
Ar is selected from the group consisting of aryl or heteroaryl radicals, having from 4 to 10 carbon atoms, e.g. phenyl, thienyl, furanyl, pyridyl, benzothienyl, benzofuranyl, naphthyl, or substituted derivatives of said aryl or heteroaryl radicals, wherein the substituents maybe selected from the group consisting of C1-C5 alkyl, halogen, CF3, CN, NO2, NR2, CO2R and OR and R3 is R, OR, CH2OR or COR.
These compounds are useful for treating diseases and conditions which are responsive to treatment with prostaglandin analogues, e.g. glaucoma; cardiovascular; e.g. acute myocardial infarction, vascular thrombosis, hypertension, pulmonary hypertension, ischemic heart disease, congestive heart failure, and angina pectoris; pulmonary-respiratory; gastrointestinal; reproductive and allergic diseases; osteoporosis and shock.
In a further aspect, the present invention relates to an ophthalmic solution comprising a therapeutically effective amount of a compound of formula (I), wherein the symbols have the above meanings, or a pharmaceutically acceptable salt thereof, in admixture with a non-toxic, ophthalmically acceptable liquid vehicle, packaged in a container suitable for metered application.
In a still further aspect, the present invention relates to a pharmaceutical product, comprising
a container adapted to dispense its contents in a metered form; and
an ophthalmic solution therein, as hereinabove defined.